Reducing sheet breaks at roll coaters



Aprll 30, 1968 M. A. KEYES ETAL REDUCING SHEET BREAKS AT ROLL COATERS 3 Sheets-Sheet l Filed Jan.

\|m1|hw 05527 J ze HY L@ %AM%I ATTORNEYS April 30, 1968 M. A. KEYES ETAL RBDUCING SHEET BREAKS AT ROLL COATERS Filed Jan. 5. 1966 I N VEN T0125 L sa j 40 Mz u. n O) J 1,; ab, MT ANLYS April 30, 1968 M. A. KEYES ETAL 3,380,431

REDUCING SHEET BREAKS AT ROLL COATERS Filed Jan. 1966 5 Sheets-Sheet 5 F/fse JNVENTORS ./a /l/l/a/v KEYES m' ad( ATTORNEYS United States Patent Office 3,38,43l Patented Apr. 30, 1968 3,380,431 REDUCING SHEET BREAKS AT ROLL CATERS Marion A. Keyes, South Beloit, Ill., and Robert J. Farrell, Beloit, Wis., assignors to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Jan. S, 1966, Ser. No. 518,802 2 Claims. (Cl. 11S- 8) ABSTRACT OF THE DKSCLOSURE An apparatus for detecting flaws in a travelling paper web or the like and for adjusting subsequent work stations in the machine automatically so that the web is not broken at the flaw and marking and readjusting the machine after the flaw has passed the subsequent station.

This invention relates generally to a method of and apparatus for detecting liaws in a travelling paper web or the like and more particularly to a method of and system for detecting variations in the characteristics of a travelling paper web and for causing a sequencing of separate corrective functions without interruption of thernovement of the paper web.

During the manufacture of paper, various defects may result in the finished paper web which are not only undesirable, but which may cause difficulties in the subsequent stages of the paper making process. In particular, defects in a paper web result in the occurence of breaks during the subsequent operations in the paper making process. When Ia break occurs in a travelling paper web, of course, the paper machine must be stopped and corrective action taken to lfeed the broken leading edge of the paper web to a subsequent station. Quite often, however, corrective action cannot be made immediately and the paper following the break may begin to pile up.

One of the most likely places for such a break to occur is at the blade coater section of a paper machine. In the coating section, the paper web passes between two rolls, one of which is partially immersed in a coating solution and the other of which serves as a backup roll to apply the correct pressure in the nip formed with the coating roll. The coating roll is supported in a pan havling the coating solution therein and is usually spring loaded and biased toward the backing roll with the paper web passing therebetween. Since it is usually desirable to coat both sides or surfaces of the paper web, two coaters are provided in tandem relationship with one another. Each of the coaters is provided with a coater blade which removes any excess coating solution from the paper web. The coater blade is also spring loaded and biased to allow a predetermined thickness of the coating solution to remain on the paper web.

A major portion of the paper breaks which occur `at the blade coater section of a paper machine are directly attributable to shock lumps, foreign matter, holes, slime spots, and other paper defects present in the sheet prior to entering the coaters.` Since the spring loaded blade scrapes the paper web, any defects present therein will catch the blade edge and tear the p-aper web. Once the tear begins, the torn portion will usually not pass over the blade edge resulting in the tear extending across the entire width of the paper web. Immediately, the paper web begins to pile up in the coater section and the paper machine must be stopped and the accumulated portion removed and discarded. The leading edge of the paper web must be threaded into the nip in a subsequent station before operation can be commenced. Therefore, not only is a great amount of manufacturing time lost, but large portions of the paper web must be discarded.

Therefore, a need exists for a method and apparatus for reducing the number of sheet breaks at blade coaters which occur due to paper defects. It is desirable that this method and apparatus allow continuous operation of the paper machine so as to eliminate losses of manufacturing time in the production of paper.

It is therefore, an object of this invention to provide a system which detects flaws in a travelling paper web and, in accordance with such detection, causes corrective action within the paper machine.

Another object of the present invention is to provide a system which detects flaws in a travelling paper web at a station ahead of a paper working device and, in accordance with such detection, causes inactivation of the paper working device during the passage of the defective paper web therethrough.

Still another object of the present invention is to provide a system which detects flaws in a travelling paper web in a paper machine at a station ahead of paper web coaters and, in accordance with such detection, inactivates the coaters during the passage of the defective paper web therethrough.

Yet another object of the present invention is to provide a system which detects flaws in a travelling paper web in a paper machine and inactivates coater blades from contact with the paper web during the passage of the detective paper web thereover.

And still a further object of the present invention is to provide a system which detects aws in a travelling paper web and, in accordance with such detection, causes marking of the defective area on the paper web.

It is still a further object of the present invention to provide a system which detects flaws in a travelling paper web and, in accordance with such detection, inactivates a paper working device during the passage of the defective paper web therethrough, and after a predetermined time. reactivates the paper working device to allow continued operation of the paper making machine.

An important object of the present invention is to provide a method of eliminating Ipaper web breaks in a paper machine without disturbing the continuous operation of the paper making machine.

An important feature of the present invention resides in the provision of an averaging circuit connected to the ilaw detector to provide a comparison signal which varies with changes in the basis weight of the lpaper web.

These and other objects, features and advantages ofthe present invention will be more fully realized and understood from the following detailed description when taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a block diagram of one embodiment of a flaw detector system constructed in accordance with the principles of the present invention;

FIGURE 2 is a block diagram of another embodiment of the flaw detector system constructed in accordance with the principles of the present invention;

FIGURE 3 is a simplied block diagram of the comparator circuit employed in conjunction with the system of FIGURE 2;

FIGURE 4 is a simplied block diagram of a sequencing module which is employed in conjunction with the flaw detector systems illustrated in FIGURES 1 and 2; and

FIGURE 5 is a simplified block diagram of a data conditioning circuit constructed in accordance with the principles of the present invention.

Like reference numerals throughout the various views of the drawings are intended to designate the same or similar structures. K

Shown in FIGURE 1 is one embodiment of a defect detector system which is constructed in accordance with the principles of this invention. A web 11 is delivered to a coater 12 by suitable rolls (not shown) which do not form a part of the invention. Upon leaving the coater 12, the web 11 is delivered to a second coater 13 by suitable roll means.

Particular types of paper require coating on one or both sides of the paper web in accordance with specified requirements. For purposes of illustration, the coater 12 coats one side of the web 11 while the coater 13 coats the opposite side thereof. Each of the coaters 12 and 13 are provided with a roller assembly which picks up the coating fluid and delivers it to the web 11 passing therethrough in a manner well known in the art. Also, the coaters 12 and 13 are provided with a wiper blade (not shown) which contacts the web 11 passing7 therethrough for removing excess coating material from the web.

A light source 16 is positioned over the web 11 by suitable fixture means (not shown). A light sensitive pickup element 17 is positioned adjacent the light source 16 with the web 11 passing therebetween for receiving light energy which is transmitted through the web 11. The amount of light energy sensed by the pickup element 17 is indicative of the density or thickness of that portion of the web 11 which passes directly between the light source 16 and the pickup element 17.

It will be understood that the light source 16 may represent a plurality of light sources extending the width of the Web 11 and similarly, the pickup element 17 may comprise a plurality of pickup elements extending the width of the web 11.

Should that portion of the web 11 passing between the light source 16 and pickup element 17 have holes therein or be relatively thin, the pickup element 17 will sense the increased light energy passing through the web 11. When a predetermined amount of light is detected by the element 17, a signal is produced and supplied to a sensing relay 18. The point at which the element 17 will provide such an actuating signal is controlled by adjustment means 20 which is associated with the pickup element 1'7. The adjustment means 20 may be either automatic or manual, depending upon the system in which employed.

The sensing relay 18 actuates a sequencing module 21 which is provided with suitable timing and delay means to perform the desired sequencing operation. The sequencing module may be either of the solid state type or of the type having timing motors and relays.

One of the output signals from the sequencing module 21 is delivered to a mark sheet control 23, which is associated with the coaters 12 and 13, to mark the defective portion of the web 11. Also, the sequencing module 21 delivers a signal to a roll and pan assembly control 24 which disengages the coating rollers from the web passing through the coater or lowers the pan of coating fluid,

whichever is most practical and desirable. Still another output signal from the sequencing module 21 is delivered to a blade control which moves the wiper blade of the coaters 12, 13 ont of engagement with the web 11 so that the blade does not contact the defective portion of the web. Still another output signal from the sequencing module 21 is delivered to a timer or footage control 26. The control 26 allows a predetermined length of the web 11 to pass through the coaters 12 and 13 after which the control 26 produces an output signal which initiates the operation of a sequencing module 29. This allows a sutlicient length of the web 11 to pass through the coaters 12 and 13 so as to insure that the defective portion of the web 11 is not coated and does not come in contact with the wiper blade therein.

After the predetermined length of web has passed through the coaters 12 and 13 the timer or footage control 26 delivers a suitable signal to the sequencing module 29, whereupon the sequencing module 29 feeds back a signal to the control 26 through a line 30 thereby stopping and resetting the timer or footage control, whichever is desired.

The sequencing module 29 provides a plurality of output signals to energize the components of the coaters 12 and 13 so as to place the coaters 12 and 13 into condition for coating the web 11 passing therethrough. An output signal from the sequencing module 29 is delivered to a blade control 31 which actuates the blade in such a manner as to place the blade in contact with the web 11 passing through the coaters 12 and 13. Also, a signal from the sequencing module 29 is delivered to a pan and roll assembly control 32 for raising the pan or the roll or both in such a manner as to place coating fluid on the web 11 passing through coaters 12 and 13. Still another output signal from the sequencing module 29 is delivered to a sheet marker control 33 thereby stopping the marking of the defective portion of the web 11. The control signal which is delivered to the sheet marker control 33 is also delivered to the sensing relay 18 via `a reset line 35 for resetting the sensing relay to an off condition. This places the sensing relay 18 and the sequencing module 2.1 in readiness to be actuated should a defective portion of the web 11 pass between the light source 16 and the pickup element 17.

Therefore, the defect detector system of the present invention provides means for sensing the change of the consistency of the web 11 passing between the light source 16 and the pickup element 17 thereby generating a control signal indicative to the change of consistency of the web. This control signal inactivates the coaters 12 and 13 so as to insure that the web 11 passing therethrough does not break or tear while passing through the coaters.

ln operation, the signal developed by the pickup element 17 is used to control the sensing relay 18 which, in turn, initiates the operation of the sequencing module 21. The sequencing module 21 then provides control signals to first, energize the marked sheet control 23 which marks the web 11 in the area of the defect; second, energize the roll and pan assembly control 24 thereby ceasing the application of coating uid to the web 11; third, energize the blade control 25 which disengages the Wiper blade within each of the coaters 12 and 13 from engagement with the web 11 passing through the respective coaters; and fourth, energize the timer or footage control 26 which measures a predetermined length of the defective portion of web 11 and thereafter automatically initiates the sequencing module 29, which, in turn, delivers a control signal back to the control to stop and re-set the control 26.

The sequencing module 29 provides a plurality of control signals for first, actuating the blade control 31 to position the wiper blade in each of the coaters 12 and 13 into engagement with the web 11 passing through the respective coaters; second, to actuate the pan and roll assembly control 32 to raise the pan and roll so as to apply coating fluid to the web 11 passing through each of the coaters 12 and 13; and third, to actuate the sheet marker control 33 thereby stopping the marking of the web 11. The control signal delivered to the sheet -marker control 33 is also delivered to the sensing relay 18 in such a manner as to reset the sensing relay 18 to place it in condition for reactuation by the pickup element 17 in the event that another defective area of the web 11 passes between the light source 16 and the pickup element 17.

Shown in FIGURE 2 is another embodiment of the defect detector system which is constructed in accordance with the principles of this invention. A web 51 is delivered to a pair of coaters 52 and 53 which apply coating solution to the web 51 during the manufacture of paper. In route to the coaters 52 and 53, the web 51 passes between a light source 56 and a pickup element 57. The light source 56 and pickup element 57 function to detect any irregularities or defects in the web 51 before such defects enter the coaters 52 and 53. A data conditioning control 58 senses the average value of the signals delivered thereto by the pickup element 57 and compares the average value with an instantaneous value which is also delivered thereto by the pickup element 57. Should the instantaneous value of the signal applied to the control 58 be suficiently different from the average value developed within the data conditioning control 58 a suitable error signal is produced. This comparison feature allows compensation for any basis weight variation over a substantial length oi the paper web.

The error signal developed by the data conditioning control 58 is delivered to a comparator 59 which compares the error signal with preset limits which may be set by the operator by a limits control 60 connected to the comparator 59. Should the error signal exceed the predetermined limit set by the limits control 60 a signal is developed by the comparator which is delivered to a sequencing module 62 thereby initiating the operation thereof.

The operation of the sequencing module 62 may be substantially similar to that of the operation of the sequencing module 21, of FIGURE 1. The output of the sequencing module 62 is delivered to the coaters 52 and 53 as indicated by line 63 to perform the necessary operation to disable the coaters 52 and `53 as the effective portion of the web 51 passes therethrough. Specifically, the sequencing module 62 starts the sheet markers, lowers the roll and pan assembly, and disengages the wiper blade from contact with the web 51 within the coaters 52 and 53.

The sequencing module 62 also delivers the start signal to a timer or footage counter 67 which controls the amount of time or length of web passing through the coaters 52 and 53. The length of the web passing through the coaters 52 and 53 during this time interval may be considered the defective portion of the web.

A set control 68 controls the limits of the timer or footage control to any `desired predetermined range. The output of the control 67 is delivered to a sequencing module 70. Upon initiation of the sequencing module 70 a reset control signal is fed back to the timer or footage control 67 through a line 71 thereby placing the control 67 in condition for reactuation by the sequencing module 62.

The sequencing module 70 may be constructed in substantially the same manner as the sequencing module 29, of FIGURE 1. The output of the sequencing module 70 is delivered to the coaters 52 and 53 as indicated by a line 72. Specifically, the squenching module first actuates the Wiper blade and places it into contact with web 51 passing through the rollers 52 and 53; second, raises the roll and pan assembly so as to apply coating solution to the web 51; and third, stops the sheet marker from applying marking dye or the like to the sheet 51.

The data conditioning control 58 and the limits control 60 may be controlled individually by manual means or by la suitable se'rvo system and corresponding computer as necessary.

Shown in FIGURE 3 is a simplified block diagram of the comparator circuit 59, of FIGURE 2 constructed in accordance with the principles of this invention. The comparator 59 is provided with an amplier 80 having a pair of input leads 81 and 482. T-he input lead 8-1 is connected toa source of voltage through .a potentiometer 85. The error signal from the data conditioning con-trol 58, of FIGURE 2, is delivered to the line 82. The lamplifier 80 senses the relative difference between the applied voltage on line 81 and the error signal applied to line 82 in such a manner las to produce an output signal when the difference between the two input signals is of a predetermined value. The output of amplifier 80 is then delivered to a rel-ay coil 86 through a diode 87. A movable contact 88 is associated with the relay coil 86 and is used to initiate the operation of the sequencing module 62, of FIGURE 2.

Shown in FIGURE 4 is a simplified block diagram of a sequencing module such as 62 constructed in accordance with the principles of this invention. The output of the comparator 59 is delivered to aline 89 Iand therefrom to a relay coil which actuates a pair of contacts 91 and 92. The contact 91 is connected to la suitable actuating means so 'as to initiate the lowering of the pan and roll, and to start the sheet marker as mentioned hereinabove.

The contact 92 delivers a reference voltage to a timer 95 which is used to allow a suitable time interval to expire .after the lowering of the pan and roller before the wiper blade is lowered. The reference voltage applied to the timer 95 is variable by a potentiometer 96 which, in turn, may vary the time duration of the timer 95. The output of timer 95 is then delivered to an amplifier 97 through a line 98. A reference voltage is also delivered to the amplifier 97 through Ia potentiometer 919. The amplifier 97 may be a differential amplifier thereby sensing the voltage difference between the input signal from line 98 and the reference voltage through potentiometer 99. The output of amplifier 97 is then delivered to a relay coil 100 through a diode 101. Associated with the relay coil 100 is a contactor 102 which is used to initiate operlation of suitable actuating means to lower the wiper blade within the coaters.

Shown in FIGURE 5 is a simplified block diagram of the data conditioning circuit 58 constructed in accordance with the principles of this invention. The output of the pick-up element 57 is delivered to a circuit point 105 where the signal information is divided into two branches. The first branch of the signal information is delivered to a filter circuit 106 which filters the continuously changing sign-al information into an average value signal. The other branch of the input sign-a1 is delivered to an analog summer 107. The output of the filter circuit 106 is also delivered to the analog summer 107. The analog summer senses variations between the average value of the input signal as applied thereto through the filter 106 and the instantaneous value of the input signal as applied thereto directly from the pickup element. Therefore, should a large vari-ation in the input signal occur a suitable error signal is developed by the analog summer 107 and delivered to the comparator 59, of FIGURE 2 as mentioned hereinabove.

Although a specific embodiment of the invention has been described herein, it is not intended to limit the invention solely thereto, but to include all of the obvious variations and modifications within the spirit and scope of the -appended claims.

We claim:

1. A flaw detector system for a travelling web travelling between successive stations in a web working machine and compensating for such defects in a subsequent section having a web Working device comprising:

an energy source disposed adjacent the web to emit energy which impinges on the web ahead of the subsequent station,

means for detecting energy from the web,

energy comparing means connected to the means 1fbr detecting energy and producing an output signal when the detected energy reaches a predetermined level,

a sequencing module connected to the means for detecting energy from the web and producing a plurality of signals,

a roll and pan assembly at the subsequent station receiving one of the signals from the sequencing module to control the web working machine at the subsequent station,

a blade control at the subsequent station receiving a second one of the plurality of signals from the sequencing module to con-trol the web working machine at the subsequent station,

Ea web measuring means receiving a third input from the sequencing module,

a sequencing logic module receiving an output from `the web measuring means and producing a plurality of outputs,

`a. blade control at the subsequent station receiving one of the outputs from the web measuring means, and

a roll and pan lassembly at the subsequent station receiving one of the signals from the sequencing logic module.

2. In apparatus according to claim 1 a mark sheet control at the subsequent station receiving a third output from the sequencing module, and a sheet marker control at the subsequent station receiving `a third output from the sequencing logic module.

References Cited UNITED STATES PATENTS CHARLES A. WILLMUTH, Primary Examiner. 10 ROBERT I. SMITH, Assistant Examiner. 

